The only real differences between the german made diana 25 (i have a 1951 version) and gecardo (which I think was the name they used for America) and the British made ones are the German ones have two pins for the sleeve that does in the cylinder,one to hold the sleeve and one for the trigger, while the British ones have one pin to do both jobs. The German ones also have a pin in the piston that pushes against the piston head screw and will probably need drilling out if you want to remove the piston washer.
Remove sights. Remove two front stock screws and screw from front of trigger guard and take action from stock. Unscrew cocking arm lock screw and pivot screw and remove cocking arm. Unscrew barrel pivot lock screw and pivot screw and remove barrel. There is a little screw on the side of the breech block if you want to take out barrel locking plunger and its spring. Unscrew the cylinder end cam and any washers that may be behind it. The 27 has a small spacer tube about 3/4s wide. Use small screwdriver to remove triggr spring off tang on sleeve. Tap trigger pivot (on german models) and remove trigger. SEE NEXT POST